Mon 23 Mar 2009
So after the last deep discharge of the nicad pack a month ago, the pack has been very soft lately. The voltage drops quickly long before I get to work. It is winter, but tonight I found out something new. I pulled the lid off of the pack and was wondering if the 24 redtops were way over charged compared to the rest of the pack, due to their higher capacity. This would allow the pack voltage to rise quickly and not fully charge the rest of the pack. So much for that theory. I took my discharge equipment and applied a 55 amp load for 12 minutes. That discharge took out exactly 11ah out of those 24 redtops. When they were almost finished, I checked them with a DVM only to find that many of them were nearly at zero volts! No good. So I put the constant current power supply on that group of redtops at 10 amps for 3 hours. So they took on 30ah worth of charge. Some cells were venting liquid which means they were over filled. I had refilled them a while ago, not knowing they were actually low on charge, which makes them low on fluid as well. Hmmm. So I’ll look forward to a stiff pack tomorrow morning on the way to work.
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